1. Field of the Invention
This invention relates to lightweight composite fiber or filament wound tubular members and, more particularly, to tubular members having continuous fibers or filaments wound around an area to define an opening in the side of the tubular member so as to orient such fibers around the opening so that the fasteners which pass through these openings apply loads which can be carried in tension by the continuous fibers and a method and apparatus for manufacturing such tubular members.
2. Description of the Prior Art
Fiber or filament wound pressure vessels, casings or tubular members have been known and used for several years and are in particular demand because of their lightweight, high strength characteristics. In using the casings or tubular members with other items, such as with a nozzle of a rocket, or any other type of end closure, it is necessary to attach the casing to the metal end of the item. Several attaching methods have been tried, such as drilling a plurality of openings through the one end portion of the wall of the casing through which pins or bolts were passed for attachment to the metal end of the nozzle. This attachment failed, due to the failure of the resin system used to bond the fibers to one another. The resin bond of fiber to fiber is not capable of carrying large loads therefore the pins or bolts were pulled out through this relatively weak fiber reinforced resin.
Another method of attaching a casing to a metal tube or to another casing is to provide interior or exterior threads on the casing which are threaded to a sleeve or collar on the tube or other casing. These forms of attachment, likewise, failed before the desired loads could be transferred from the one casing to the other.
Still another known method of attachment provided for forming a continuous recess in the casing near one end thereof into which a flange on a connector projecting from a tube seats and is clamped therein by a split ring clamp. This attachment also failed to meet the required transfer of loads from one casing to another.
A further method of reinforcing the wall of a fiber wound pressure vessel in the vicinity of an opening drilled therethrough is to place between each layer of fiber a ring of concentrically wound fiber with the openings in each ring aligned so that the fiber wound vessel can be drilled in line with the openings in the rings. The resulting vessel has better pressure rupturing capacity, but it is still far short of that desired.